3.9 KiB
Control Flow
A drum pattern that plays the same sound on every step is not very interesting. You want kicks on the downbeats, snares on the backbeats, hats filling the gaps. Control flow is how you make decisions inside a step.
if / else / then
The simplest branch. Push a condition, then if:
step 4 mod 0 = if kick s . then
Every fourth step gets a kick. The rest do nothing. Add else for a two-way split:
step 2 mod 0 = if
kick s 0.8 gain .
else
hat s 0.3 gain .
then
These are compiler syntax -- you won't find them in the dictionary. Think nothing of it.
? and !?
When you already have a quotation, ? executes it if the condition is truthy:
{ snare s . } coin ?
!? is the opposite -- executes when falsy:
{ hat s 0.2 gain . } coin !?
These pair well with chance, prob, and the other probability words:
{ rim s . } fill ? ;; rim only during fills
{ 0.5 verb } 0.3 chance ? ;; occasional reverb wash
ifelse
Two quotations, one condition. The true branch comes first:
{ kick s . } { hat s . } step 2 mod 0 = ifelse
Reads naturally: "kick or hat, depending on whether it's an even step."
{ c3 note } { c4 note } coin ifelse
saw s 0.6 gain . ;; bass or lead, coin flip
pick
Choose the nth option from a list of quotations:
{ kick s . } { snare s . } { hat s . } step 3 mod pick
Step 0 plays kick, step 1 plays snare, step 2 plays hat. The index is 0-based.
{ c4 } { e4 } { g4 } { b4 } step 4 mod pick
note sine s 0.5 decay .
Four notes cycling through a major seventh chord, one per step.
case / of / endof / endcase
For matching a value against several options. Cleaner than a chain of ifs when you have more than two branches:
step 8 mod case
0 of kick s . endof
4 of snare s . endof
endcase
Steps 0 and 4 get sounds. Everything else falls through to endcase and nothing happens.
A fuller pattern:
step 8 mod case
0 of kick s 0.9 gain . endof
2 of hat s 0.3 gain . endof
4 of snare s 0.7 gain . endof
6 of hat s 0.3 gain . endof
hat s 0.15 gain .
endcase
The last line before endcase is the default -- it runs when no of matched. Here it gives unmatched steps a ghost hat.
The of value can be any expression:
step 16 mod case
0 of kick s . endof
3 1 + of snare s . endof
2 4 * of kick s . snare s . endof
endcase
times
Repeat a quotation n times. @i holds the current iteration (starting from 0):
4 { @i 4 / at hat s . } times ;; four hats, evenly spaced
Build chords:
3 { c4 @i 4 * + note } times
sine s 0.4 gain 0.5 verb . ;; c4, e4, g#4
Subdivide and accent:
8 {
@i 8 / at
@i 4 mod 0 = if 0.7 else 0.2 then gain
hat s .
} times
Eight hats per step. Every fourth one louder.
Putting It Together
A basic drum pattern using case:
step 8 mod case
0 of kick s . endof
2 of { hat s . } often endof
4 of snare s . endof
6 of { rim s . } sometimes endof
{ hat s 0.15 gain . } coin ?
endcase
Kicks and snares on the strong beats. Hats and rims show up probabilistically. The default sprinkles ghost hats.
A melodic step that picks a scale degree and adds micro-timing:
{ c4 } { d4 } { e4 } { g4 } { a4 } step 5 mod pick
note
step 3 mod 0 = if
0 0.33 0.66 at ;; triplet feel on every third step
then
saw s 0.4 gain 0.3 decay 0.2 verb .
A times loop paired with case for a drum machine in one step:
4 {
@i case
0 of kick s . endof
1 of hat s 0.3 gain . endof
2 of snare s . endof
3 of { rim s . } 0.5 chance endof
endcase
@i 4 / at
} times
Four voices, four sub-positions, one step.